Markedly Enhancing Adrenal Pseudotumor: IgG4‐Related Disease

A 30‐year‐old man presented with left flank discomfort and an incidentally identified 3.5‐cm left adrenal mass. He reported a history of unexplained xerophthalmia and ocular pain; however, physical examination, adrenal hormonal workup, and tumor markers were unremarkable. Abdominal computed tomography (CT) revealed a 3.3 × 3.5 × 3.2 cm, well‐circumscribed, homogeneous soft‐tissue mass without calcification or cystic components (Figure 1A). Contrast‐enhanced CT demonstrated marked heterogeneous arterial enhancement (Figure 1B), followed by persistent, intense, and homogeneous enhancement (Figure 1C,D); notably, the attenuation in the venous phase reached 115 HU. Suspecting a pheochromocytoma, a retroperitoneal laparoscopic adrenalectomy was performed.

FIGURE 1.

Imaging and pathological findings of the left adrenal mass. (A) Unenhanced CT shows a well‐defined mass in the left adrenal region (arrows). (B) Contrast‐enhanced CT in the arterial phase demonstrates marked, heterogeneous enhancement (arrows). (C) The venous phase exhibits progressive, intense, and homogeneous enhancement (arrows) peaking at 115 HU. (D) The delayed phase reveals persistent intense enhancement (arrows). (E) H&E staining (×100) displays diffuse lymphoplasmacytic infiltration, predominantly plasma cells, with storiform fibrosis. (F, G) Immunohistochemistry (×400) shows IgG and IgG4 positivity, featuring > 100 IgG4+ plasma cells per high‐power field and an IgG4/IgG ratio > 40%.

Histopathology revealed dense lymphoplasmacytic infiltration and characteristic storiform fibrosis without evidence of malignancy (Figure 1E). Immunohistochemistry demonstrated > 100 IgG4‐positive plasma cells per high‐power field, with an IgG4/IgG ratio > 40% (Figure 1F,G). A diagnosis of IgG4‐related disease (IgG4‐RD) was established (total score: 33 points per the 2019 ACR/EULAR criteria). Serum IgG4, measured on postoperative day 3, was 2120 mg/L (reference < 1350 mg/L). Given complete resection of the adrenal mass and no definitive extra‐adrenal systemic involvement aside from mild ocular symptoms of unknown cause, no additional systemic glucocorticoid treatment was administered. At the 3‐month follow‐up, serum IgG4 levels had normalized, and abdominal CT revealed no recurrence.

IgG4‐related disease is a systemic condition predominantly affecting the digestive system, lacrimal glands, etc.; however, focal adrenal involvement is rare [1]. Previously, the only confirmed IgG4‐related adrenal pseudotumor was a calcifying fibrous tumor (CFT), with typical pathological features including extensive fibrosis, scant lymphoplasmacytic infiltration, and definite calcification [1]. In contrast, this case exhibited less extensive fibrosis, diffuse lymphoplasmacytic infiltration, and no calcification, which is inconsistent with CFT. However, some pathologists have hypothesized that this condition may represent an early stage of CFT [2].

Notably, the radiological features of IgG4‐related adrenalitis remain poorly defined. Our case demonstrates that this condition can manifest as an inflammatory pseudotumor, appearing as a well‐defined, homogeneous mass with marked and persistent enhancement. Given its rarity, further research and reports are needed to elucidate its detailed clinicopathological and radiological evolution.

Author Contributions

Xiaofang Liu: data curation, writing – original draft. Yanzhen Sun: investigation, formal analysis. Weiwei Liao: conceptualization, methodology, writing – review and editing, supervision, project administration.

Funding

The authors have nothing to report.

Conflicts of Interest

The authors declare no conflicts of interest.

Data Availability Statement

The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions.